Now here is something interesting. It appears that Valve has accidentally released a prototype version of the first Left 4 Dead game. Yeap, PC gamers can – at least for now – play a prototype version of this Zombie game.

So, in the latest update for Counter-Strike 1.6, Valve accidentally included the prototype version of Left 4 Dead, called “Terror Strike”. And, as you may have guessed, PC gamers figured out how to launch and play it.

Valve accidentally compiled and pushed earliest Left 4 Dead prototype called "Terror Strike" into the latest CS 1.6 update and community figured out how to play it. pic.twitter.com/llVkYCip69

— ‎Gabe Follower (@gabefollower) November 23, 2023

Now as you will see, this prototype version of Left 4 Dead is basically Counter-Strike with zombies. Terror Strike looks and plays similar to CS. So, don’t expect it to be similar to the final version of Left 4 Dead. Regardless of that, it can give you an idea of how Left 4 Dead actually started.

I don’t know whether this was done on purpose. I also don’t know if Valve plans to remove Terror Strike from the game. Thankfully, we’ll get even more videos from this prototype version of Left 4 Dead, so that’s at least something.

It’s also worth noting that this isn’t the first time we’ve seen this prototype version of Left 4 Dead. In January 2023, Valve leaked this map in Counter-Strike: Global Offensive. So, that’s two for two for Valve.

I also love playing prototype versions of older titles. For years we’ve been asking for the prototype/alpha versions of Duke Nukem Forever. Yes yes, there is currently a restoration project for it. However, I’d also love to play its Quake 2 version.

Anyway, this is a cool leak so make sure to give Terror Strike a go if you own Counter-Strike 1.6.

Stay tuned for more!